The Mineral magnesite

The most common form of Magnesite is white, microcrystalline, porous masses that are dull in luster, and have the appearance of unglazed porcelain. Because they are porous, they adhere to the tongue when licked.

An interesting Magnesite occurrence is in Brumado, Brazil, where a deposit of clear, well formed, rhombohedrons similar to Iceland SparCalcite found. Until this find, such crystals were, although identical in appearance to Iceland SparCalcite, they are much rarer and sought after. Common Iceland Spar Calcite has been wrongly labeled by some unscrupulous dealers as Magnesite to stimulate sales.

- Iron rich variety of Magnesite, containing a greater amount of magnesium over iron. Its chemical formula is (Mg,Fe)CO3. If the amount of iron exceeds the magnesium, the mineral is called Sideroplesite which is a magnesium rich variety of Siderite.

Magnesite is an important ore of magnesium, and used as insulating material. White Magnesite is also used as a minor collectors gemstone, polished into beads and spheres as well as carved into figures. These forms of Magnesite often have black or brown rock veins running through the mineral.

In Australia good Magnesite comes from Mt. Bischoff, Waratah, Tasmania; and in China good specimens were found at Shangbao, Hunan Province.
Clear crystals, identical in appearance to the Iceland Spar variety of Calcite, occur at Brumado, Bahia, Brazil, which is perhaps the most famous occurrence of this mineral.

Calcite- The rare transparent Magnesite rhombohedrons appear identical to Calcite%, but can be distinguished by the slight hardness difference, and more efficiently by the fact that Calcite effervesces even in cold and diluted hydrochloric acid, whereas Magnesite only in hot, undiluted hydrochloric acid.Dolomite- Cannot be distinguished from Magnesite by ordinary methods. However, Dolomite usually forms as curved crystals, whereas Magnesite does not.

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